Conventional heavy oil upgrading via hydroprocessing uses relatively inefficient large extrudate catalyst pellets to support the reactions. It has long been recognized that there are significant advantages to using a finely divided slurry catalyst for heavy oil upgrading via hydroprocessing. Past attempts to demonstrate slurry heavy oil hydroprocessing on a large scale have relied on upflow reactors employing bubble column technology. However, such reactors suffer from difficulty in maintaining the desired dispersed bubble flow regime necessary for efficient reactor volume utilization. Past problems with bubble column reactors and difficulties in maintaining the desired bubble flow regime has hindered the development of slurry heavy oil upgrading via hydroprocessing.
In heavy oil hydroprocessing in the prior art, upflow reactors have been used. U.S. Pat. No. 6,278,034 discloses a process in which a reactor contains a slurry bed, and feed is added at the bottom of the reactor. U.S. Pat. Nos. 6,454,932 and 6,726,832 disclose hydrocracking of heavy hydrocarbons in upflow reactors containing ebullating catalyst beds in series. U.S. Pat. No. 4,684,456 discloses an upflow reactor employing an expanded catalyst bed. The expansion of the bed is automatically controlled by automatically changing the rate of speed of a recycle pump for the reactor. There is no teaching in this patent of the use of such a reactor with a slurry.
U.S. Pat. No. 6,660,157 discloses a process for slurry hydrocracking employing a series of upflow reactors with interstage separation. The reactors are not liquid recirculating reactors, such as those employed in the instant invention.
In one embodiment, the invention relates to a novel use for a liquid recirculating reactor in upgrading heavy oils, particularly the upgrade of heavy oils employing an active catalyst composition in a slurry form, as admixed with heavy oil feedstock. In another embodiment, the invention relates to a method to upgrade heavy oils employing a liquid recirculating reactor, which does not employ any slurry bed, and where a slurry catalyst and feed mixture is added at the bottom of the reactor.